Abstract: The hydrolysis of casein by HCl was systematically studied through orthogonal test design.Some factors of influencing hydrolytic efficiency were also examined.It was found that hydrolytic time was the dominant influence factor, and the concentration of HCl was middle as well as the ratio of liquid to solid had relative small effects.The optimum hydrolytic conditions were 18hrs of hydrolytic time, 18%~20% of HCl 1.6:1 of the ratio of liquid to solid.The hydrolysate of casein was reacted with glucose to form flavoring materials.Aroma and taste of cigarette smoke were improved significantly by adding the Maillard reaction products to tobacco shred.